LESION OP DIFFERENT REGIONS OF THE CEREBRAL HEMISPHERES. 505 
gyrus causes only the same temporary loss or impairment of vision as occurs from 
lesion of the angular gyrus alone. 
Complete removal of the occipital lobe and greater portion of the angular gyrus on 
one side causes temporary blindness in the opposite eye, followed by bilateral 
hemiopia towards the side opposite the lesion. This ceases to be perceptible a few 
weeks after the operation. Recovery ensues even if the other angular gyrus is also 
considerably injured. 
It appears, therefore, that vision is possible with both eyes when only portions of 
the visual centres remain on both sides. 
SECTION II. 
Lesions of the Temporo-Sphenoidal Convolutions. 
Experiment 13* (Plate 22, figs. 23-38). 
In this animal the superior temporo-sphenoidal convolution was exposed in both 
hemispheres, and both were destroyed by means of the actual cautery directed along 
their course with the aid of a director. 
The animal had recovered consciousness by the time the dressings, &c., were com¬ 
pleted. The eyes were open, the pupils equal and contractile, and the conjunctival 
reflex distinct on both sides. 
Within half an hour after the operation it began to look about, and approaching 
the bars of the cage, laid hold and climbed up hand-over-hand. When its hands or 
feet were touched with the point of a pencil it withdrew them, evidently conscious of 
the impressions. 
Two hours after the operation the animal seemed perfectly well, climbing about 
actively. It tried to lay hold of the pencil with which its hands or feet were touched, 
with a view of testing its cutaneous sensibility. 
It, however, paid not the slightest attention to or gave any indications of hearing the 
loudest sounds of various kinds made in its vicinity—sounds which invariably startled 
the other Monkeys near it. 
Next day there was some oedema of the eyelids, but the animal evidently enjoyed 
perfect vision. It gave also clear evidence of perception of a touch anywhere on its 
body. Oil of bergamot held under its nostrils caused it to sniff and make movements 
of its lips, as if it smelt and liked it. Acetic acid caused it to withdraw its head, 
and snort or sneeze out. Salt placed on its lips caused it to make tasting movements. 
As before, not the slightest sign of perception could be caused by any sounds made 
in its vicinity. 
On the fourth day the various tests were repeated. In every respect the animal 
w r as perfectly normal except as regards hearing. No sign of hearing could be elicited. 
It was noted that while the other Monkeys eagerly listened to the footsteps of any 
MDCCCLXXXIV. 3 T 
